변별로 설정 시 오류 수정

src/hooks/roofcover/useRoofShapeSetting.js

@@ -735,32 +735,36 @@ export function useRoofShapeSetting(id) {
     const index = lines.findIndex((line) => line.idx === selectedLine.idx)
 
     const nextLine = lines[index + 1] || lines[0]
+    history.current.push(selectedLine)
     if (nextLine.attributes?.isFixed) {
       canvas.discardActiveObject()
       return
     }
-    history.current.push(selectedLine)
+
     canvas.setActiveObject(nextLine)
   }
 
   // 변별로 설정 내 일변 전으로 돌아가기
   const handleRollBack = () => {
     if (history.current.length === 0) {
+      canvas.discardActiveObject()
       return
     }
     const lastLine = history.current.pop()
+    canvas.setActiveObject(lastLine)
 
-    currentObject.set({
+    currentObject?.set({
       stroke: '#000000',
       strokeWidth: 4,
+      attributes: { isFixed: false },
     })
 
     lastLine.set({
       stroke: '#000000',
       strokeWidth: 4,
+      attributes: { isFixed: false },
     })
 
-    canvas.setActiveObject(lastLine)
     canvas.renderAll()
   }